Ignition composition



Patented Nov. 15, 1949 STATES orrice 6 Claims.

'Thepresent invention relates tobcmp'csitions of matter for thepreparation of ignition devices.

An object of the present invention is the provision of a composition ofmatter of the type specified which does not tend to jell.

Another ob ect of the invention is the provision of a composition ofmatter of the type specified which has desirable viscositycharacteristics.

other ob'jects orthe invention will be apparent from the followingdescription:

Ignition-devices are customarily prepared by surrounding hea'tableelements such as an electric bridge wire with a coating compositioncarrying a heat-sensitive ignition compound.

One'conunon type 'ofigniteris-the bridge plug type u'S'ed -in" someforms of'elec'tric detonators. A bridge plug comprises a plug ofmaterial separating two leg wires connected together by a fine, highresistance, bridge wire. A coating composition, admixed with an ignitioncompound, is spread around the bridge wire. The spreading operation iscalled buttering because of the viscous consistency of the compositioncontaining the ignition compound. The buttered material dries hard onevaporation of the solvent, and subsequent heating of the bridge wire asby passage of an electric current fires the ignition material with theproduction of a burst of flame.

Another form of igniter, also commonly used in detonators, is theelectric match which is composed of two insulated metal plates or foilsconnected together by a bridge wire and dipped in a coating compositioncontaining an ignition compound. The dipping operation forms, around thebridge wire, a drop of ignition material which hardens on drying.Electric matches also may be fired by passage of an electric currentthrough the bridge wire.

While many difierent materials are used for ignition compounds, leadsalts of nitrophenols have been found particularly desirable in manyinstances. Examples of lead nitrophenols which are particularly usefulin accordance with the present invention are lead styphnate, monobasiclead 4:6 dinitro-ortho-cresylate, monobasic lead picramate, monobasiclead 3:5 dinitro-benzoate, lead nitrato-bis-basic-lead 4:6dinitro-orthocresylate, normal lead 2 nitro-resorcinate and monobasiclead 2 nitro-resorcinate.

The coating composition which is used to carry the ignition compound isusually of the lacquer type composed of a highly combustiblenitrocarbohydrate such as nitrostarch or nitrocellulose and a volatilesolvent such as esters of the type of butyl acetate and amyl acetate,aromatic hydrocarb'ons such as'benz'ene, and the like. De pending -onthe viscosity or volatility characteris tics=desired, d'ififerent'solvents or mixtures of solvents a're used as is well understood in theart.

A difiiculty which has been found to occur wheii' lead salts ofnitroph'enols are used in lacquer'sdfthis type'has been that thecomposition tends to setup into a' gel prior to use, andin'a gelfo'rmit" is diflicult-to apply. According to'tlie present invention, it hasbeen discovered that compositions of'the present type do? not: exhibitthis gelling phenomenon when acetone or acetonyl acetone are-includedinthein. Either or both of these-materials has been found to besuccessful.

Acetonyl acetone is usually somewhat to be preferred; particularly whenthe compositions are to be used for operations of the buttering type.When buttering mixtures are prepared, it is customary to originallyprepare them in thin form and then to evaporate them to the desiredviscous consistency which makes for easy buttering. When acetone is usedin such mixtures it sometimes volatilizes away before the composition isthick enough for use. Acetonyl acetone does not show this disadvantage.

When the compositions can be used in less viscous form, as for dipping,acetone is found to be entirely satisfactory.

While acetone and acetonyl acetone may be used as sole solvents, it isusually preferred that they be used in proportions of from about 1 toabout 20% by volume based on the total volume of the compositionexcluding ignition compounds.

The following example is illustrative of a specific embodiment of theinvention:

A lacquer was made up by adding 2.4% by weight of nitrostarch to asolvent which was composed of 95% butyl acetate and 5% benzene. 180 cc.of this lacquer were mixed with 200 grams of lead styphnate and 20 cc.of acetonyl acetone. This mixture was partially dried until it becameviscous and then was buttered on to the bridge wires of bridge plugs. Atno time did the composition exhibit any jelling tendency and it butteredreadily. After drying, the igniters produced were found to be entirelysatisfactory.

A composition particularly suitable for the preparation of match headsmay be made by using a lacquer composed of nitrocotton dissolved in amylacetate and by substituting acetone for acetonyl acetone. As is wellunderstood in the art, it is usually desirable to protect match heads bydips of protective coating. A first protective dip of a 6 oz. etheralcohol nitrocotton lacquer, and

about 1 to about 20% by volume of the composi- I tion exclusive ofignition compound.

2. A composition of matter comprising nitrocotton, a volatile solventtherefor, an anti-gelling agent selected from the class consisting ofacetone and acetonyl acetone, and an ignition compound selected from thegroup consisting of lead styphnate, monobasic lead 4:6dinitro-ortho-cresylate, monobasic lead picramate, monobasic lead 3:5dinitro-benzoate, lead nitrato-bis-basic-lead 4:6dinitro-ortho-cresylate, normal lead 2 nitroresorcinate and monobasiclead 2 nitro-resorcinate, said anti-gelling agent comprising from about1 to about 20% by volume of the composition exclusive of ignitioncompound.

3. A composition of matter comprising lead styphnate, butyl acetate,benzene, acetonyl acetone, and nitrostarch.

'4. A composition of matter comprising a nitrocarbohydrate in solution,acetonyl acetone as an anti-gelling agent and an ignition compoundselected from the group consisting of lead styphnate, monobasic lead 4:6dinitro-ortho-cresylate, monobasic lead picramate, monobasic lead 3:5dinitro-benzoate, lead nitrato-bis-basic-lead 4:6dinitro-ortho-cresylate, normal lead 2 nitroresorcinate and monobasiclead 2 nitro-resorcinate, said anti-gelling agent comprising from about1 to about 20% by volume of the composition exclusive of ignitioncompound.

5; A composition of matter comprising a combustible nitrocarbohydrate, avolatile solvent therefor, an anti-gelling agent selected from the classconsisting of acetone and acetonyl acetone, and an ignition compoundselected from the group consisting of lead styphnate, monobasic lead 4:6dinitro-ortho-cresylate, monobasic lead picramate, monobasic lead 3:5dinitro-benzoate, lead nitrato-bis-basic-lead 4:6dinitro-orthocresylate, normal lead 2 nitro-resorcinate and monobasiclead 2 nitro-resorcinate, said antigelling agent comprising from about 1to about 20% by volume of the composition exclusive of ignitioncompound.

6. A composition of matter according to claim 5 in which saidanti-gelling agent is acetonyl acetone.

WILLIAM D. TREVORROW.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,045,012 Flurscheim Nov. 19,1912 1,964,077 Piccard June 26, 1934 2,159,229 Rubenstein May 23, 1939

